Police helicopter crashes onto Glasgow pub
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Does the FADEC on the 135 permit any manual control of throttle position or is it simply off, idle and fly?
Imagine for a second that the collective is 'stuck' at a significantly high pitch setting. With engines driving the aircraft can't descend without significant speed increase. How therefore do you establish a controlled descent? In the old days of manual throttles you could reduce Nr to induce a rate of descent but if the choice is either fly or idle its a little trickier.
Imagine for a second that the collective is 'stuck' at a significantly high pitch setting. With engines driving the aircraft can't descend without significant speed increase. How therefore do you establish a controlled descent? In the old days of manual throttles you could reduce Nr to induce a rate of descent but if the choice is either fly or idle its a little trickier.
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Sat in aircraft right now, with both gens switched off COM1 NAV1 and ADF drop out, even though avionics switches are on. Fact.
Yes, manual control is possible and practised
Yes, manual control is possible and practised
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jayteeto
Sat in aircraft right now, with both gens switched off COM1 NAV1 and ADF drop out, even though avionics switches are on. Fact.
(Sorry, I just thought a tiny bit of banter wouldn't go amiss)
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Thomas Coupling #1128
"In answer to a previous enquiry about Gazelle fenestron stall: The EC135 [it being a mix of the German BO105 and the French Aerospatialle]. The phenomenon experienced by some Gazelle drivers was machined out when it came to the 135 by champfering the edge of the fenestron ring thus widening the "acceptance angle" of the fenestron and reducing (not fully eliminating) the risk of 'fenestron stall'. "
TC, many thanks for clearing up that question - glad the designers made some progress to eliminate FS in subsequent designs. I remember the occasional white faces of Gazelle drivers, who had fallen out of high hovers over Belfast in the small hours back in the 80s. One chap said he had just input some yaw and was adamant that he wasn't going backwards (very difficult to judge at 6000ft and inadvertently going backwards was the common reason for them ending up looking at the city through their roof Perspex!!) He regained control after gyrating back to positive airspeed but he thought he had lost yaw control. We had some serious respect for those guys trying to do that job without any auto stab control.
Kbc
TC, many thanks for clearing up that question - glad the designers made some progress to eliminate FS in subsequent designs. I remember the occasional white faces of Gazelle drivers, who had fallen out of high hovers over Belfast in the small hours back in the 80s. One chap said he had just input some yaw and was adamant that he wasn't going backwards (very difficult to judge at 6000ft and inadvertently going backwards was the common reason for them ending up looking at the city through their roof Perspex!!) He regained control after gyrating back to positive airspeed but he thought he had lost yaw control. We had some serious respect for those guys trying to do that job without any auto stab control.
Kbc
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Low Fuel and no reaction to perform an auto
Hi
We have a few facts here, low fuel and low Nr. Both are key factors in this kind of accident. I dont say Pilot was unprofesional, but all we know that fuel lights are common operating ec135.
Press Release April 9, 2013
We have a few facts here, low fuel and low Nr. Both are key factors in this kind of accident. I dont say Pilot was unprofesional, but all we know that fuel lights are common operating ec135.
Press Release April 9, 2013
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Banter welcome!
I raise the point because there has been discussion about this previously. I stated that if he 'lost' both engines and put out a mayday on COM1, nothing would go out. Someone else told us that with avionics on, you would have both radios. We were both correct, it all depends on what you want fitted to the battery and avionics busbar. I guess its a customer choice.
These discussions cause arguments and insults, but also educate.........
I suggest pilots go out asap and turn the generators off, see what YOU lose on YOUR aircraft. That's why it is sometimes healthy to speculate and not 'wait for the AIB report'. I know for certain now.
I raise the point because there has been discussion about this previously. I stated that if he 'lost' both engines and put out a mayday on COM1, nothing would go out. Someone else told us that with avionics on, you would have both radios. We were both correct, it all depends on what you want fitted to the battery and avionics busbar. I guess its a customer choice.
These discussions cause arguments and insults, but also educate.........
I suggest pilots go out asap and turn the generators off, see what YOU lose on YOUR aircraft. That's why it is sometimes healthy to speculate and not 'wait for the AIB report'. I know for certain now.
Avoid imitations
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So under NPAS, may a pilot may find himself flying supposedly identical aircraft that react differently in emergency situations?
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Rotor Speed on impact
There is a lot of talk about the Nr and how on earth it could be at zero during this accident, so I thought that I would put my thoughts, knowledge and experience into the mix.
There is only a very very small chance that the rotor brake was applied in flight. Even if it was, it is not man enough to stop the rotors with engine(s) running, so a fire would start. An example of this was two early Merlins that crashed due to being engulfed in fire after rotor brake malfunctions. It is my understanding that this aircraft has a purely manual rotor brake, so a malfunction can also be ruled out. Therefore, only a rotor brake application after double engine failure/shutdown could be applicable in this scenario, but has a zero probability of likelihood. Lets rule the rotor brake out of this shall we?
So why zero Nr? There has been many situations following engine failure/shutdown that have required engine-off landings (EOL). The vast majority have been fully or somewhat successful, but there are a few that have ended in disaster due to various factors. In these accidents, one common theme has been the very low or zero Nr on impact. Most have been put down to incorrect or modified EOL technique due to the location and/or environment, but some have been put down to the fact that practice autorotations are done to a highish hover rather than to the ground, so when it is required for real, the pilot flies to the hover rather than the ground, because that is what he is used to (cognitive training).
Having reached the EOL hover with a high collective pitch angle, Nr decays rapidly and with lift being proportional to V^2, the aircraft descends rapidly with no collective left to cushion the touchdown in the last 20 feet. Even a drop from this height can result in a 50G impact and a resulting negligible Nr as the high drag from max pitch slows the Nr to a halt. There is evidence of this from at least two fatal accidents that I am aware of.
That accounts for the zero Nr, but what it doesn't do is account for the choice of EOL site...........
There is only a very very small chance that the rotor brake was applied in flight. Even if it was, it is not man enough to stop the rotors with engine(s) running, so a fire would start. An example of this was two early Merlins that crashed due to being engulfed in fire after rotor brake malfunctions. It is my understanding that this aircraft has a purely manual rotor brake, so a malfunction can also be ruled out. Therefore, only a rotor brake application after double engine failure/shutdown could be applicable in this scenario, but has a zero probability of likelihood. Lets rule the rotor brake out of this shall we?
So why zero Nr? There has been many situations following engine failure/shutdown that have required engine-off landings (EOL). The vast majority have been fully or somewhat successful, but there are a few that have ended in disaster due to various factors. In these accidents, one common theme has been the very low or zero Nr on impact. Most have been put down to incorrect or modified EOL technique due to the location and/or environment, but some have been put down to the fact that practice autorotations are done to a highish hover rather than to the ground, so when it is required for real, the pilot flies to the hover rather than the ground, because that is what he is used to (cognitive training).
Having reached the EOL hover with a high collective pitch angle, Nr decays rapidly and with lift being proportional to V^2, the aircraft descends rapidly with no collective left to cushion the touchdown in the last 20 feet. Even a drop from this height can result in a 50G impact and a resulting negligible Nr as the high drag from max pitch slows the Nr to a halt. There is evidence of this from at least two fatal accidents that I am aware of.
That accounts for the zero Nr, but what it doesn't do is account for the choice of EOL site...........
@TC
I believe if my mind serves me well they are also configured along two tip path planes (similar to the Apache et al).
I believe if my mind serves me well they are also configured along two tip path planes (similar to the Apache et al).
By the way, the EC135 is a mixture between BO 108 and Aerospatial. The BO 108 was the planned replacement of the 105.
skadi
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Mick S, Your hypothesis fits with my opinion on this event. Choice of LS really becomes "wherever the aircraft ends up pointing" after a flare and lever dump depending on height/time. A minor adjustment to point the aircraft at the clearest looking area may be all one has time to do. Then the real challenge to judge the height to flare and check - at night and possibly without a rad alt or one which is getting scatter info off the ground and other buildings. Just doesn't bare thinking about. How many of us have ever tried EOL at night? Not me - only autos to full flare recoveries or we would have broken too many aircraft. So once placed in the total power loss situation - skill/luck/experience becomes merged and I think luck becomes the primary factor. Why the total loss of power - that is the AAIB first question to answer and what they have said so far just really states that they have no evidence - yet.
Kbc
Kbc
without a rad alt or one which is getting scatter info off the ground and other buildings.
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Scatter. Sorry a bad phrase really - what I mean is the radar altimeter giving readings off a building then the ground as you fly over the urban area. This causes the radar altimeter readings to jump as all the Tx/Rx is doing is bouncing signals off whatever is below the aircraft. Sorry for the poor terminology. Perhaps this type of issue has been alleviated in modern software driven rad alts?
Kbc
Kbc
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Its not the first time that aircraft would have different fits. Even though individual NPAS units specced their own aircraft, I doubt that there is that much difference between them. With the 135, the avionics fits differ A LOT, whenever I fly another units aircraft I use some of my travel day to sit in it and see what systems are on board. Twin inverters, T2/2+/2+e, GNS430, std radio, transponder, nav fit/GPS, lights, station box, radar, chelton/handheld, which tac channel, MRT radio. As we all know PPPPPP
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Just some observations, as my brain is too tired of theorising, especially when there's so much going round in circles, and repetition. There is always merit in reading & understanding all previous posts before suddenly having an idea that was posted by someone else 3 days (maybe 10 pages) ago!
DAPT - would be nice if EC could release a Training Manual at sensible cost. I've seen a very out of date one (T1 & P1 only - although most systems are the same) but understand that when someone investigated an up-to-date version, they were quoted EU6,000 - for a CD!! I would have expected this to have been provided with the aircraft - it's a miniscule part of the £3-4m that operators paid for the airframe and an invaluable training aid, from the one I saw. It would not be difficult to put it on the t.i.p.i. site, and easier to update.
Some have mentioned Simulator training. The pilot in this case, being a Bond employee, will most likely have conducted a useful part of both his initial, and recurrent, training in the excellent facility at Staverton. Depending on the outcome of the investigation, it may be more value is placed on such training?
It has been hinted by others, but some less familiar with 135 systems may wish to understand that pressing the FIRE button (or actually de-pressing, as the button comes out, rather than goes in) requires a wire lock to be broken & a flap to be lifted, before the button can be pressed - No2 button is fairly easy to reach, No1 is more of a stretch.
The engine then takes some time to think about shutting down, as all the button does is close the LP cock, and actuate the Fire system (it'll only fire the bottle if there's still a fire detected below 50% N1). It takes a frustrating number of seconds for the engine to actually wind down, certainly if you want to get rid of the torque - which is why pilots will elect to use throttles as the quickest, and most to-hand, method of killing unwanted power.
Re training EOLs, by day or night. I think TC mentioned some good reasons why not but, in addition, we need to remember that twin engine machines are optimised for POWERED flight. Everything in the design works towards keeping the rotors powered, so that a powered landing can be made safely, including the (theoretically) idiot-proof fuel system with all its warnings & different sized tanks [No implication in the "i" word]. The rotor system is optimised for this and, while it will auto, it's a low-inertia system, as has already been explained. It's another issue to put to bed, as it's completely impractical.
And the discussion about two pilots should be put to bed for a while - it wasn't very long ago that two pilots found themselves in the water and we've been operating single pilot Police Ops very safely, all over the UK, for many years. Not sure of total hours flown, but would suggest something in the region of 25,000 per year for at least 15 years, plus a good bit before that - say 0.5m hours (back of a plain fag-packet calc. only). Not totally without incident/accident but, as with all aviation, there are risks identified and managed, or they wouldn't be able to get insurance.
DAPT - would be nice if EC could release a Training Manual at sensible cost. I've seen a very out of date one (T1 & P1 only - although most systems are the same) but understand that when someone investigated an up-to-date version, they were quoted EU6,000 - for a CD!! I would have expected this to have been provided with the aircraft - it's a miniscule part of the £3-4m that operators paid for the airframe and an invaluable training aid, from the one I saw. It would not be difficult to put it on the t.i.p.i. site, and easier to update.
Some have mentioned Simulator training. The pilot in this case, being a Bond employee, will most likely have conducted a useful part of both his initial, and recurrent, training in the excellent facility at Staverton. Depending on the outcome of the investigation, it may be more value is placed on such training?
It has been hinted by others, but some less familiar with 135 systems may wish to understand that pressing the FIRE button (or actually de-pressing, as the button comes out, rather than goes in) requires a wire lock to be broken & a flap to be lifted, before the button can be pressed - No2 button is fairly easy to reach, No1 is more of a stretch.
The engine then takes some time to think about shutting down, as all the button does is close the LP cock, and actuate the Fire system (it'll only fire the bottle if there's still a fire detected below 50% N1). It takes a frustrating number of seconds for the engine to actually wind down, certainly if you want to get rid of the torque - which is why pilots will elect to use throttles as the quickest, and most to-hand, method of killing unwanted power.
Re training EOLs, by day or night. I think TC mentioned some good reasons why not but, in addition, we need to remember that twin engine machines are optimised for POWERED flight. Everything in the design works towards keeping the rotors powered, so that a powered landing can be made safely, including the (theoretically) idiot-proof fuel system with all its warnings & different sized tanks [No implication in the "i" word]. The rotor system is optimised for this and, while it will auto, it's a low-inertia system, as has already been explained. It's another issue to put to bed, as it's completely impractical.
And the discussion about two pilots should be put to bed for a while - it wasn't very long ago that two pilots found themselves in the water and we've been operating single pilot Police Ops very safely, all over the UK, for many years. Not sure of total hours flown, but would suggest something in the region of 25,000 per year for at least 15 years, plus a good bit before that - say 0.5m hours (back of a plain fag-packet calc. only). Not totally without incident/accident but, as with all aviation, there are risks identified and managed, or they wouldn't be able to get insurance.
Last edited by zorab64; 11th Dec 2013 at 08:35. Reason: Add comments to posts made while typing!
Avoid imitations
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I posted having thought along similar lines about the fenestron, but it was quickly pointed out that the AAIB had stated all mechanical parts were accounted for.
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Police crew personal radios
I'm interested in what the two crew members might have said to their control during the sortie and especially in the immediate run up to the impact.
Having watched a fair number of TV progs following Police ASU operations it appears that, whilst the PIC maybe using VHF, the other crew members are plugged in to a network that gives them instant voice comms to a variety of other police officers on the ground.
I've seen no mention of this source of information in the public domain and yet I'm sure any such recordings will have been secured as part of the Police SOPs.
Harrowing as any transmissions may have been, could there be some form of narrative going on? And if there was nothing coming from them that would be equally significant.
SGC
Having watched a fair number of TV progs following Police ASU operations it appears that, whilst the PIC maybe using VHF, the other crew members are plugged in to a network that gives them instant voice comms to a variety of other police officers on the ground.
I've seen no mention of this source of information in the public domain and yet I'm sure any such recordings will have been secured as part of the Police SOPs.
Harrowing as any transmissions may have been, could there be some form of narrative going on? And if there was nothing coming from them that would be equally significant.
SGC
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Fenestron detail
I wonder is anyone able to post drawings showing fenestron internals, please? Have seen photo from port side with lid off showing hydraulics and electrics within hub. Unable to find pics or drawings of gearbox.
Many Thanks!
henry_crun
non-aviator, ex-industry
Many Thanks!
henry_crun
non-aviator, ex-industry